Lubricant compositions containing organo mercaptoalkyl borates



United States l atent f) 3 383,130 LUBRICANT COMPOSITIONS CONTAINING ORGANO MERCAPTOALKYL BORATES Frederick E. Seypinski, Monroeville, and Harold 0.

Strange, Penn Hills Township, Allegheny County, Pa.,

assignors to Gulf Research 8; Development Company,

Pittsburgh, Pa, a corporation of Delaware No Drawing. Filed Nov. 2, 1965, Ser. No. 506,127

9 Claims. (Cl. 252-463) This invention relates to an improved lubricant for use in internal combustion engines and more particularly to a lubricating composition having improved extreme pressure and antiwear characteristics.

In the design of modern engines, machinery, and the like, the engineer is constantly striving for improvements with respect to compactness, speed, power and acceleration. In achieving these improvements closer tolerances are being employed between adjacent moving surfaces. In order to prevent undue wear and perhaps even seizure of the adjacent surfaces, a lubricating composition is -required which will form a lubricating film between the respective surfaces. The lubricating film must be able to Withstand extremely high pressures without being squeezed from between the surfaces and without being decomposed.

We have discovered that a lubricating composition having improved antiwear and load-carrying characteristics can be obtained by incorporating into a lubricating oil a small amount of an organo mercaptoalkyl borate having the general formula wherein R is selected from the group consisting of hydrogen, alkyl, aryl, alkary-l, aralky-l and cycloaikyl radicals containing 1 to 16 carbon atoms and n is an integer of 2 to 16, inclusive. The R substituents may be either alike or different. From the standpoint of ease in preparation, it is preferred to employ those compounds where the R groups are of the same kind.

Specific examples of the radicals which we intend to include with respect to R in the above formula are as follows: hydrogen; methyl; ethyl; propyl; isopropyl; n butyl; sec-buty-l; tertiary butyl; amyl; hexyl; heptyl; n-octyl; isooctyl; nonyl; decyl; undecyl; dodecyl; tridecyl; tetradecyl; pentadecyl; 'hexadecyl; pheny-l; l-naphthyl; Z-naphthyl; o-, m-, and p-tolyl; m-, and p-xylyl; methylnaphthyl; dimethylnaphthyl; tri-, tetra-, penta-, and hexamethylnaphthyl; o-, m-, and p-ethylphenyl; o-, m-, and p-propylphenyl; o-, m-, and p-butylphenyl; o-, m-, and p-amylphenyl; o-, m-, and p-hexylphenyl; o-, m-, and p-heptylphenyl; 0-, n1-, and p-octy-lphenyl; 0-, m-, and p-nonylphenyl; diethylphenyl; dipropylphenyl; dibutylphenyl; diamylphenyl; triethylphenyl; tripropylphenyl; tetraethylphenyl; pentaethylpheny-l; benzyl; phenethyl; gamma-phenylpropyl; naphthylethyl; o-, m-, and p-methylbenzyl; 0-, 111-, and p-methylphenethyl; cyclopentyl; cyclohexyl; cyclooctyl; methylcyclohexyl; and the like.

The organo substituents of the organo mercaptoalkyl borates can be selected from a variety of the organic radicals mentioned above on the basis of their ability to impart oil-solubility to the compounds. Specific examples of some of the organo mercaptoalkyl borates represented by the above formula are tri (mercaptoethy hborate tri(methylmercaptoethyl)borate tri(ethylmercaptoethyl borate tri(propy-lrnercaptoethyl)borate tri (butylmercaptoethyl borate tri( hexylmercaptoethylyb orate tri octylmercaptoethyl borate tri( decylmercaptoethyl borate tri( dodecylmerc aptoethyl) borate tri (hexadecylmercaptoet-hyl borate tri (phenylmercaptoethyl borate tri(naphthylmercaptoethyl) borate tri (tolylmercaptoethyl borate tri (ethylphenylmercaptoethyl) borate tri nonylphenylmercaptoethyl borate tri benzylme-rcaptoethyl) borate tri (cyclohexylmercaptoethyl borate di mercaptoethyl) mono (-methylmercaptoethyl) borate di mercaptoethyl) mono (ethylmerc aptoethyl borate di(mercaptoethyl) mono(propylmercaptoethyl)borate di mercaptoethyl) mono(butylmercaptoethyl) borate di (mercaptoethyl) mono(hexylmercaptoethyl) borate di (rnercaptoethyl) mon o( octylmercaptoethyl) borate di (me-rcaptoethyl) mono( do decylmercaptoethyl borate di (rnercaptoet'hyl) mono( hexadecylmercaptoethyl) borate di(mercaptoethyl) mono( phenylmercaptoethyl borate di merca-ptoethyl) mono(tolylmercaptoethyl) borate di mercaptoethyl) mono(nonylphenylmercaptoethyl) borate di (merc aptoethyl) di (mercaptoethyl) borate mono(mercaptoethyl) di-( met'hylmercaptoethyl)borate mono(mercaptoethyl) di (ethylmercaptoethyl) borate mono( mercaptoethyl) di propylmercaptoet-hyl) borate mono( mercaptoethyl) di (butyl-mercaptoethyl) borate mono(mercaptoethyl) di (hexylmercaptoethyl) borate mono(mercaptoethyl) di (octylmercaptoethyl borate mono(mercaptoethyl) di(dodecylmercaptoethyl)borate mono mercaptoethyl) di (hexadecylmercaptoethyl) borate mono mercaptoethyl) di phenylmerc aptoethyl )-b0rate mono (mercaptoethyl) di (tolylme-rcaptoethyl) borate mono(mercaptoethyl) di (nonylphenylmercaptoethyl) borate mono(mercaptoethy-l) di(benzylmercaptoethyl) borate mono (mercaptoethyl) di cyclohexylmercaptoethyl) borate tri mercaptopropyl borate tri (methylmercaptopropyl borate tri ethylmercaptopropyl borate tri (propylmercaptopropyl borate tri butylmercaptopropyl borate tri (hexylmercaptopropyl borate tri octylmercaptopropyl borate tri decylmercaptopropyl) borate tri dodecylmercaptopropyl borate tri(hexadecylmercaptopropyl borate tri(phenylmercaptopropyl borate tri( naphthylmercaptopropyl borate tri( tolylmercaptopropyl) borate tri(ethylphenylmercaptopropyl borate tri(nonylphenylmercaptopropyl borate tri( benzylmercaptopropyl borate tri(cyclohexylmercaptopropyl) borate di (mercaptopropyl) mono methylmercaptopropyl borate di(mercaptopropyl) mono (ethylmercaptopropyl borate di (mercaptopropyl) mono pr-opylmercaptopropyl borate di(mercaptopropyl) mono butylmercaptopropyl borate di (mercaptopropyl) mono hexylmercaptopropyl borate di(mercaptopropyl) mono octylmercaptopropyl) borate di(mercaptopropyl) mono dodecylmercaptopropyl)borate di(mercaptopropyl) mono (hexadecylmercaptopropyl) borate di(mercaptopropyl) mono (phenylmercaptopropyl borate di(mercaptopropyl) mono (tolylmercaptopropyl) borate mono (benzyl-mercaptoethyl borate mono (eyelohexy-lmercaptoethyl) di(mercaptopropyl) mono(nonylphenylmercaptopropyl) borate di(mercaptopr-op'yl) mono(benzylmercaptopropyl)borate di mercaptopropyl) mono cyclohexylmercaptopropyl) borate mono (mercaptopropyl) di(methylmercaptopropyl)borate mono (mercaptopropyl) di ethylmercaptopropyl borate mono mercaptopropyl) di propylmercaptopropyl borate mono (mercaptopropyl) di butylmercaptopropyl borate mono mercaptopropyl) di hexylmercaptopropyl )borate mono (mercaptopropyl) di octylrnercaptopropyl borate mono(mercaptopropy1) di(dodecylmercaptoprpyl)borate mono (mercaptopr-opyl) di(hexadecylmercaptopropyl) borate mono (mercaptopropyl) di (phenylmercaptopropyl) borate mon0(mercaptopropyl) di(tolylmercaptopropyl)borate mono (mercaptopropyl) di nonylphenylmercaptopropyl) borate mono (mercaptop ropyl) di benzylmercaptopropyl borate mono(mercaptopropyl) di(cyclohexylmercaptopropyl) borate tri(mercaptobutyl)borate tri methylmercaptobutyl borate tri (ethylmercaptobutyl) borate tri(propylmercaptobutyl)borate tri butylmercaptobutyl borate tri(hexylmercaptobutyl)borate tri(octylmercaptobutyl)borate tri(decylmercaptobutyl)borate tri(dodecylmercaptobutyl)borate tri(hexadecylmercaptobutyl)borate tri(phenylmercaptobutyl)borate tri( naphthylmercaptobutyl borate tri(tolylmercaptobutyl)borate tri ethylphenylmercaptobutyl borate tri(nonylphenylmercaptobutyl)borate tri(benzylmercaptobutyl)borate tri(cyclohexylmercaptobutyl)borate di(rnercaptobutyl) mono(methylmercaptobutyl)borate di mercaptobutyl) mono (ethylmercaptobutyl) borate di(mercaptobutyl) mono (propylmercaptobutyl)borate di(mercaptobutyl) mono(butylmercaptobutyl)borate di mercaptobutyl) mono (hexylmercaptobutyl borate di mercaptobutyl) mono octylmercaptobutyl borate di(mercaptobutyl) mono(dodecylmercaptobutyl)borate di (mercaptobutyl) mono (hexadecylmercaptobutyl') borate di(mercaptobutyl) mono(phenylmercaptobutyl)borate di(mercapt-obutyl) mono(tolylmercapt0butyl)borate di(mercaptobutyl) mono(nonylphenylmercaptobutyl) borate di(mercaptobuty1) mono(benzylmercaptobutyl)borate di(mercaptobutyl) mono(cyclohexylmercaptobutyl) borate mono (mercaptobutyl) di (methylmercapt-obutyl borate mono (mercaptobutyl) di ethylmercaptobutyl borate mono(mercaptobutyl) di(propylmercaptobutyl)borate mono(mercaptobutyl) di(butylmercaptobutyl)borate mono(mercaptobutyl) di(hexylmercaptobutyl)borate mono (mercaptobutyl) di octylmercaptobutyl borate mono mercaptobutyl) di (dodecylmercaptobutyl borate mono(n1ercaptobutyl) di(hexadecylmercaptobutyl)borate mono(mercaptobutyl) di(phenylmercaptobutyl)borate mono (mercaptobutyl) di(tolylmercaptobutyl borate mono(mercaptobutyl) di(nonylphenylmercaptobutyl) borate mono (mercaptobutyl) di (benzylmercaptobutyl borate mono(mercaptobutyl) di(cyclohexylmercaptobutyl)borate tri(mercaptoamyl)borate tri(mercaptohexyl)borate tri(mercaptoheptyl)borate tri(mercaptooctyl)borate tri(mercaptononyl)borate tri(mercaptodecyl)borate tri( mercaptoundecyl borate tri(mercaptododecyl)borate 4 tri(mercaptotridecyl)borate tri(mercaptotetradecyl)borate tri(mercaptopentadecyl)borate tri (mercaptohexadecyl borate While all of the organo mercaptoalkyl borates mentioned hereinabove can be employed for improving the antiwear and load-carrying characteristics of an oil, it is not to be implied that all such compounds serve with equal efficiency. Those organo mercaptoalkyl borates having the general formula B(OCH CH SR) wherein R is hydrogen or an alkyl radical containing from 1 to 12-carbon atoms form a preferred group of compounds. Especially good results are obtained, for example, with tri(mercaptoethyl)borate and tri(dodecylmercaptoethyl) borate.

The amount of the organo mercaptoalkyl borate compound employed may vary over wide limits depending upon the particular compound employed, the type of base oil in which the compound is incorporated and the severity of the conditions to which the ultimate composition is subjected. In general, however, we use an amount between about 0.5 and 10 percent by weight based on the weight of the oil. Good results are obtained with about 1 to about 5 percent by weight of the organo mercaptoalkyl borate compound. In any event, the organo mercaptoalkyl borate is employed in an amount sufficient to improve the antiwear and extreme pressure characteristics of the oil to which the compound is added. When used in amounts of about 0.5 to about 10 percent by weight, the organo mercaptoalkyl borate also serves as an oxidation inhibitor.

The organo mercaptoalkyl borates can be prepared according to known chemical procedures. Neither the compounds per se nor their method of preparation constitutes any portion of this invention. The organo mercaptoalkyl borates, for example, can be prepared by reacting boric acid with one or more of the appropriate thioalcohols under reflux conditions in a suitable solvent such as a liquid hydrocrabon, e.g., benzene, toluene or the like. The reaction is continued until the theoretical amount of Water is formed. Theoretically, complete reaction of the boric acid and alcohol requires 3 moles of the alcohol for each mole of boric acid. Thus, the reaction is theoretically complete when 3 moles of Water are formed for each mole of boric acid used. When the theoretical amount of water is collected, the heating process is discontinued and the solvent evaporated from the product. No catalyst is required. The reaction of the boric acid and thioalcohol occurs readily at temperatures in the range of about 40 to about 200 C. The reaction is preferably conducted at atmospheric pressure. It will be recognized that when organo mercapotalkyl borates with the same organic radicals are desired, a single thioalcohol is employed. When organo mercaptoalkyl borates with different organic radicals are desired, two or more thioalcohols may be utilized separately or as mixtures thereof. In any event, the total amount of alcohol employed to eifect esterification should be sufficient to replace the three hydrogen atoms of the boric acid. While we have disclosed a method of preparing the organo mercaptoalkyl borates by reacting boric acid with the appropriate thioalcohol or mixture of thioalcohols, other methods of preparing the organo mercaptoaikyl borates can be employed without deviating from the scope of the invention provided the resulting esters have the general formula disclosed hereinabove. Suitable thioalcohols for use as starting materials include organo mercaptoalkanols such as mercaptoethanol, methylmercaptoethanol, ethylmercaptoethanol, propylmercaptoethanol, butylmercaptoethanol, octylmercaptoethanol, dodecylrnercaptoethanol, hexadecylmercaptoeth a n o l phenylmercaptoethanol, tolylmercaptoethanol, benzylmercaptoethanol, cyclohexylmercaptoethanol, mercaptopropanol, methyl'mercaptopropanol, mercaptobutanol, mercaptopentanol, mercaptohexanol, mercaptoheptanol,

fnercaptooctanol,

Example 1 A mixture of 6.2 grams (0.1 mole) of boric acid, 23.4 grams (0.3 mole) of 2-mercaptoethanol and 100 ml. of

benzene was refluxed at about 80 C. in a flask connected to a reflux condenser by means of a Dean-Stark trap.

The water which formed during the reaction was collected as a benzene azeotrope. When 5.2 ml. of water was col- 'lected (theory is 5.4 ml.), the reaction was terminated and the benzene was stripped off under reduced pressure. The product thus obtained was a clear liquid weighing 23.4 grams (96% yield). Elemental analysis of the product shows it to compare favorably with the theoretical analysis of tri(2-mercaptoethyl)borate as follows:

Percent by weight for B(OCH CH SH) Found: Carbon, 28.0; hydrogen, 6.1; sulfur, 37.5; boron, 4.4. Theoretical: Carbon, 29.8; hydrogen, 6.2; sulfur, 39.8; boron, 4.5.

Example 11 A mixture of 76.2 grams (2.34 moles) of 2-n-d0- decylmercaptoethanol, 48.8 grams (0.78 mole) of boric acid and one liter of toluene was refluxed at about 110 C. in a flask connected to a reflux condenser by means of a Dean-Stark trap. The water which formed during the reaction was collected as a toluene azeotrope. When 43 ml. of water was collected (theory is 42.2 ml.), the reaction was terminated, the solution filtered and the toluene removed under reduced pressure. The product thus obtained was a clear liquid which solidified slowly to a wax on standing. The product weighed 582 grams a (99+% yield). Elemental analysis of the product shows it to compare favorably with the theoretical analysis of tri(2-dodecylmercaptoethyl)borate.

Percent by weight for B(OCH CH SC H Found: Carbon, 65.91; hydrogen, 10.80; boron, 1.47. Theoretical: Carbon, 67.5; hydrogen, 11.65; boron, 1.47.

The lubricating oil to which the organo mercaptoalkyl borate is added to form a lubricating composition having' improved antiwear and extreme pressure characteristics can be any oil of lubricating viscosity such as refined or semirefined parafiinic, naphthenic or asphalt base oil. Hydrotreated mineral oils, because of their improved stability over untreated oils are especially prefered lubricating bases for preparing lubricants to be used under moderately elevated temperatures. When temperatures in the order of 400 F. and above are to be encountered, synthetic oils of lubricating viscosity form a preferred class of lubricating oil bases to which the organo mercaptoalkyl borate is added. Thus, synthetic lubricating oils such as polymerized oleflns, organic esters such as di-Z-ethylhexyl sebacate and di-Z-ethylhexyl azelate and the like can also be used as the base oil to form a lubricating composition in accordance with the invention. If desired, a blend of oils of suitable viscosity can be employed instead of a single oil, by means of which any desired viscosity can be secured.

The lubricating composition of our invention can contain minor amounts of other agents normally added to lubricating oils for a specific purpose such as a dispersant, a detergent, a pour point depressant, a thickener,

-a corrosion inhibitor, a viscosity index improver, an

antifoamant, a rust inhibitor, a dye and the like. The

lubricating composition can also contain oiliness and other extreme pressure agents and antioxidants to further enhance the lubricating characteristics if desired.

To prepare an improved lubricating composition the additives disclosed herein can be added to the lubricating oil base directly or in the form of an oil concentrate in an amount to give the desired concentration in the final 6 lubricating composition. Slight heating of the mixture may be advantageously employed to facilitate blending of the additives in the com-position.

To demonstrate the effectiveness of the organo mercaptoalkyl borates of the type described hereinabove, we have conducted comparative tests, the results of which are listed in Table I, with a mineral lubricating oil alone and with the same oil blended with representative organo mercaptoalkyl borates. The mineral oil employed had the following typical inspection:

Gravity, API 32.2 Viscosity, SUS Sec.:

F. 153.0 210 F. 44.0 Flash OC, F. 440 Fire 00, F. 490

In illustrating the improved antiwear and load-carrying characteristics, tests were made using the four-ball wear test. In conducting this test, a four ball wear test machine was employed. In this machine, three steel balls are securely fastened in contact with each other in a horizontal plane in a cup. A fourth steel ball in a rotating spindle is placed so that it is entirely supported by the other three balls forming -a pyramid. The test cup is placed on a stage which can move vertically to facilitate loading. The stage rests on a calibrated fulcrum so that specific weights may be applied to force the three balls in the cup to contact the rotating fourth ball at a predetermined pressure. The cup holding the three balls also contains the test lubricant at a level of 2 mm. above the stationary balls, thus assuring an adequate supply of lubricant at the contact points. A fixed oil temperature is maintained by a relay system connected to a thermocouple in the cup and a heater in the stage. The fourth Iball can be rotated from a motor drive at 600, 1200 or 1800 r.p.m. Each test is run with new steel .balls. I

A test is run on a lubricant at a specific load, temperature, speed and time. Lubricating properties are evaluated from an examination of (1) the scars on the clean surfaces of the three stationary balls, the two maximum right angle diameters of each wear scar being measured to the closest 0.01 millimeter and averaged and (2) the load in kilograms at which seizure occurs. A more complete description of the machine and test method are given in the Naval Research Laboratory Report entitled A Study of the Four Ball Wear Machine, by W. C. Clinton, NRL Report 3709, September 1950.

In illustrating the improved antiwear and load-carrying characteristics of compositions of the invention by the four ball wear test, the movable ball was rotated at 1800 r.p.m. for one hour while maintaining the test lubricant at 250 F Separate one hour tests were conducted using new steel balls at loads of 10 to 50 kilograms unless seizure was encountered. At the end of each test, wear scars were measured. The advantageous wear properties of the oil containing an additive of the invent-ion as compared with the base oil are illustrated by the data set forth in Table I.

1 Seizure.

7 It is apparent from the data in Table I that a lulbricating composition containing an organo mercaptoalkyl borate in accordance with the invention has substantially improved antiwear and load carrying characteristics as determined by the fourball wear tests.

and acid number. The compositions of the invention (Compositions E and F) also show improved viscosity indices after the 48 hour test.

Specific examples of other compositions within the scope of the invention are set forth in Table III.

Organo mereaptoalkyl borate:

Tri(methylmetcaptoethyl)borate Tri(nony1 phenylmercaptoethyl)- borate Dl(mercaptoethyl) mono(methylmercaptoethyl) borate Iri(phenylmercaptobutybborate- Mouo(mereaptoethyl) ditethylmercaptoethybborate 'Iri(mercaptohexadecybborate In addition to improved antiwear and load carrying characteristics, lubricating compositions of the invention also have improved resistance to oxidation. In order to demonstrate the effectiveness of the organomercaptoalkyl borates of the type described hereinabove as antioxidants in lubricating oils, we have conducted comparative oxidation tests with representative lubricating oils alone and with the same lubricating oils blended with representative organo mrcaptoa l kyl borates. The oxidation test was conducted by bubbling air at a rate of one liter per hour through approximately milliliters of test luibricant contained in a glass tube inserted into an aluminum block heated to 347 F. (175 C.). The duration of the test was 48 hours; The viscosity of the test lubricant and its acid number were determined at the beginning and the conclusion of each test. The percent increase in viscosity and the increase in acid number of the lubricant during the test is indicative of the oxidation stability of the test lubricant at a temperature of 347 F. under accelerated oxidizing conditions.

The results of comparative tests on a lubricating oil alone, and the same lubricating oil with an organo mercaptoalkyl borate are shown in Table II.

TABLE 11 Percent by Weight Composition D E F Diisooctyl azelate 100 99. 0 99. 0 Tri(mercaptoethyl)borate (Example I) 1.0 Trxiffodecylmercaptoethyl)borate (Example 1 0 Oxidation Test (Air flow, 1 1/l1r.):

Viscosity, cs. at 100 F.:

Initial 12. 66 12. 66 12. 28 After 48-hour test 1 22. 79 1 13.00 1 12. 55 Increase 10. 13 0. 34 0. 27 Percent Increase in Viscosity 80 2. 7 2. 2 Viscosity Index:

Initial 166 153 163 After 48-hour test 1 142 1 168 1 165 Change in viscosity index. 24 +15 +2 Acid Number (ASTM D 974):

Initial 0. 7 0.07 0.06 After 48-hour test 1 28.68 1 1. 82 1 1. 12 Increase 28. 61 1. 75 1. 06

1 Average of 2 tests.

The data in Table II clearly show that a lubricating oil normally tending to undergo oxidational changes at an elevated temperature has improved resistance to oxidational changes when a small amount of an organo mercaptoalkyl borate is present. The lubricating oils containing the tri(mercaptoethyl)borate and tri(dodecylmercaptoethyl) borate have very little increase in viscosity Although the invention has been described particularly with reference to lubricating oil compositions, it will be recognized that other lubricating compositions including oils thickened to the consistency of a grease areincluded by the invention.

While our invention has been described with reference to various specific examples and embodiments, it will be understood that the invention is not limited to such examples and embodiments and may be variously practiced within the scope of the claims hereinafter made.

We claim: I

1. A lubricating composition comprising a major amount of a lubricating oil and a small amount, sufficient to improve the antiwear and load-carrying characteristics of the oil, of an organo rnercaptoalkyl borate having the general formula S (CI-In) RS(CI-lz)uO-I 3-O(CHz)nSR wherein R is selected from the group consisting of hydrogen, alkyl, aryl, alkaryl, aralkyl and cycloalkyl radicals containing 1 to 16 carbon atoms and n is an integer of 2 to 16.

2. The lubricating composition of claim 1 wherein the organo mercaptoalkyl borate is present in an amount of about 0.5 to 10 percent by weight.

3. A lubricating composition comprising a major amount of a lubricating oil and a small amount, suflicient to improve the antiwear and load-carrying characteristics of the oil, of an organo mercaptoethyl borate having the general formula 1 B (OCH CH SR 3 wherein R is selected from the group consisting of hydrogen and an alkyl radical containing 1 to 12 carbon atoms.

4. The lubricating composition of claim 3 wherein the organo mercaptoethyl borate is tri(InercaptoethyD'borate.

5. The lubricating composition of claim 3 wherein the organo mercaptoethyl borate is tri(dodecylmercaptoethyl) borate.

6. A lubricating composition comprising a major amount of a mineral lubricating oil and about 0.5 to about 10 percent by Weight of tri(mercapt0ethyl)borate.

7. A lubricating composition comprising a major amount of a mineral lubricating oil and about 0.5 to about 10 percent by weight of tri(dodecylmercaptoethyl) borate.

8. A lubricating composition comprising a major amount of diisooctyl azelate and about 0.5 to about 10 percent by weight of tri(mercaptoethyl)borate.

9. A lubricating composition comprising a major amount of diisooctyl azelate and about 0.5 to about 10 percent by weight of tri(dodecy1mercaptoethyl)borate.

References Cited by the Examiner UNITED STATES PATENTS 10/1950 Rogers et a1. 252-463 9/1959 Ramsden 260-462 OTHER REFERENCES Organoboron Chemistry, Howard Steinberg, Interscience Publishers, New York, vol. 1, 1964, p. 27.

DANIEL E. WYMAN, Primary Examiner.

L. G. XIARHOS, Assistant Examiner. 

1. A LUBRICATING COMPOSITION COMPRISING A MAJOR AMOUNT OF A LUBRICATING OIL AND A SMALL AMOUNT, SUFFI CIENT TO IMPROVE THE ANTIWEAR AND LOAD-CARRYING CHARACTERISTICS OF THE OIL, OF AN ORGANO MERCAPTOALKYL BORATE HAVING THE GENERAL FORMULA 